The renal metabolism of beta-2 microglobulin (B2 micrograms) will be evaluated in patients with various types of renal disease and carcimoma. In addition, experimental animal studies will be conducted. Dogs will be used to study the renal handling of B2 micrograms as affected by variations in renal blood flow, glomerular filtration rate and tubular metabolism under controlled conditions. Methods will be utilized to determine the glomerular sieving coefficient and the Tm for B2 micrograms. The relationship of the filtered load to urinary excretion will be studied in patients with various renal diseases and carcinoma. Multiple large and small proteins will be measured including IgA, IgG, IgM, lysozyme, K and L chains and B2 micrograms to determine the relative filterability of B2 micrograms with various disorders of glomerular permeability and tubular metabolism. Preliminary data have demonstrated that two isoproteins of B2 micrograms occur in the urine of normal subjects and patients following cadaveric renal transplant. Variation in the excretion ratio of the two isoproteins suggested that this protein would be of use in detection of rejection reaction and response to therapy in renal transplants and in particular with various types of carcinoma. This protocol proposes to evaluate the significance of these variations in isoproteins.